A wide range of applications has been found for polyoxyalkylene-polysiloxane block copolymers, which are referred to in the following as polyethersiloxanes. They can be used as surfactants, emulsifiers, dispersants, leveling agents for paints, lubricants, auxiliary materials for the tertiary recovery of crude oil, as foam stabilizers in polyurethane foaming, as a textile auxiliary for brightening fibers, yarns or sheet-like textile products, for hydrophilizing sanitary products of textile fibers and for many other purposes.
The polyethersiloxanes therefore have manifold uses, since their properties, particularly their hydrophilic/-hydrophobic balance, can be influenced and brought to the desired value by selecting a suitable siloxane block or siloxane blocks on the one hand, and constructing the polyether block or blocks appropriately on the other.
For example, the siloxane block can be linear or branched, and the absolute number of difunctional and trifunctional siloxy units and their numerical ratio to one another can be varied within wide limits.
Aside from the polyether blocks, it is also possible to link other modifying groups to a silicon atom. Examples of such groups are long-chain hydrocarbon groups with up to 30 carbon atoms, hydrocarbon groups substituted with halogen atoms, cyano groups or polar groups, hydroxyl groups, etc.
The polyether groups can likewise have different structures. Each polyoxyalkylene block may be composed of different oxyalkylene units, primarily of oxyethylene, oxypropylene and oxybutylene units. Moreover, the molecular weight ratio of these units to one another, as well as the molecular weight of the polyoxyalkylene block, can be varied. The end group of the polyoxyalkylene block, which can be reactive (for example, an OH group) or inert (for example, an alkoxy group), is also of importance.
The polyoxyalkylene block can be linked to the polysiloxane block by a hydrolytically stable C--Si bond or by a hydrolytically less stable C--O--Si bond.
It is also possible and, for many applications, desirable to link different polyether blocks to the polysiloxane block. In this connection, the different polyether blocks differ with respect to their molecular weight and/or their hydrophilicity and/or their inert or reactive end groups.
Polysiloxanes with different polyether blocks are described, for instance, in the following patents and published patent applications:
German Patent 15 70 647: Chloropolysiloxanyl sulfates are reacted with mixtures of alkylene oxide adducts, which consist of 50 to 95 OH equivalent percent of polyalkylene glycol monoethers comprising ethylene oxide and propylene oxide units, contain 40 to 70 mole percent of oxypropylene units and have a molecular weight (M.sub.n) of 1,000 to 3,000, and the hydroxyl groups of which preferably are secondary, and of 5 to 50 OH equivalent of alkylene oxide adducts of polyhydric hydroxyl compounds with a molecular weight (M.sub.n) of 130 to 3500, the polyalkylene glycol components of which consist of ethylene oxide and/or propylene oxide units and which have an OH equivalent weight of up to 1750, and the hydroxyl groups of which preferably are secondary, the quantitative ratios being chosen so that there is at most 1.4 and, preferably, 1.05 to 1.2 OH equivalents for each acid equivalent of the chloropolysiloxanyl sulfate.
German Patent 16 94 366: This patent relates to polysiloxane-polyoxyalkylene block copolymers, the polysiloxane block of which has a conventional structure and the polyoxyalkylene block of which, however, consists of 25 to 70% by weight of a polyoxyalkylene with an average molecular weight (M.sub.n) of 1,600 to 4,000 and an ethylene oxide content of 20 to 100% by weight, the remainder being propylene oxide and, optionally, higher alkylene oxides, and 30 to 75% by weight of a polyoxyalkylene with an average molecular weight (M.sub.n) of 400 to 1,200 and an ethylene oxide content of 65 to 100% by weight, the remainder being propylene oxide and, optionally, higher alkylene oxides.
German Offenlegungschrift 25 41 865: The polysiloxane-polyoxyalkylene block copolymers are defined with respect to their polyoxyalkylene block so that one polyoxyalkylene block has an average molecular weight (M.sub.n) of 900 to 1,300 and consists of 30 to 55% by weight of ethylene oxide, the remainder being propylene oxide, and the other polyoxyalkylene block has an average molecular weight (M.sub.n) of 3,800 to 5,000 and consists of 30 to 50% by weight of ethylene oxide, the remainder being propylene oxide.
European Publication 0 275 563: The block copolymer, described in this published European patent application, comprises three different polyoxyalkylene blocks, namely one block which contains 20 to 60% by weight of oxyethylene units and has a molecular weight (M.sub.n) of 3,000 to 5,500, another block with 20 to 60% by weight of oxyethylene units and a molecular weight (M.sub.n) of 800 to 2,900, and a third,block which contains only polyoxy-propylene units and has a molecular weight of (M.sub.n) 130 to 1200.
According to the state of the art, such polyether-siloxanes can be prepared in various ways. In this connection, reference is made to the following patents:
German Patent 10 12 602: Monohydric and dihydric polyether alcohols are reacted in the presence of a solvent and a catalyst with polysiloxanes, which have terminal .tbd.Si--O-alkyl groups, the aliphatic alcohol set free being distilled off from the reaction mixture. The reaction therefore is a trans-esterification reaction.
German Patent 17 95 557: Equilibrated siloxane mixtures having the general formula R.sub.x SiO.sub.y (SO.sub.4).sub.z X.sub.4-(Z+2x+2y), wherein R is any univalent hydrocarbon group, X represents a halogen or alkoxy group, x has a value of 0.9 to 2.2, y has a value of 0.75 to 1.75 and z has a value of 0.0001to 0.5, with the proviso that 4&gt;(x+2y+2x)&gt;2, are reacted with monohydric polyether, the acid set free during the reaction is neutralized and the reaction product is filtered off and freed from solvent.
By both methods, polyethersiloxanes are obtained in which the polyether group(s) is (are) linked to the siloxane backbone over an Si--O--C bond.
The synthesis of polyethersiloxanes, in which the polyether groups(s) is (are) linked to the siloxane backbone over an Si--C bond, is given in the German patent 31 33 869. According to the method described there, allyl polyethers are reacted with polysiloxanes, which have SiH groups, in the presence of special platinum catalysts and, optionally, in the presence of inert solvents.
The invention is concerned with the technical problem of finding polyethersiloxanes, which are particularly suitable for use in hair cosmetics and can be used, in particular, as additives for hair shampoos. At the same time, a further aim is to improve the handle and the combability of the hair.